Well, you could try using the Microlite troubleshooting guide. Just don't put faith in the numbers that they give for things like ohms (that may make it hard to use, tho'). The most basic thing that you need to understand is that the ignition voltage comes from the battery during cranking, but changes over to self-generated once you let up on the start switch. So if there's no oil level switch, most likely your failure indicates no voltage getting out.
I bought my Microlite's new voltage regulator last year from "Flight Systems".... IIRC, they have some troubleshooting info on-line. A Google search should turn them up.
Jim, "Chicken Little only has to be right once."